Silverado 2500 4WD V8-8.1L VIN G (2006)
Throttle Body Assembly
The throttle body for the TAC system is similar to a conventional throttle body with a couple of exceptions. One exception being the use of a motor to
control the throttle position instead of a mechanical cable. The other exception is the new design throttle position (TP) sensor. The TP sensor mounts
on the side of the throttle body opposite the throttle actuator motor. The TP sensor is actually 2 individual TP sensors within one housing. Separate
signal, low reference, and 5.0-volt reference circuits are used to connect the TP sensors and the TAC module. The TP sensor 1 signal voltage
increases as the throttle opens, from around 1.0 volt at 0 percent throttle to above 3.5 volts at 100 percent throttle. TP sensor 2 signal voltage
decreases as the throttle is opened, from around 3.8 volts at 0 percent throttle to below 1.0 volt at 100 percent throttle.
Throttle Actuator Control (TAC) Module
The TAC module is the control center for the electronic throttle system. The TAC module and the PCM communicate via a dedicated redundant serial
data circuit. The TAC module and the PCM monitor the commanded throttle position and compare the commanded position to the actual throttle
position. This is accomplished by monitoring the APP and the TP sensor. These 2 values must be within a calibrated value of each other. The TAC
module also monitors each individual circuit of the TP sensor and the APP to verify proper operation.
